Method of making saturated gaskets



Oct. 10, 1939.

E. c. SCHACHT ET AL METHOD OF MAKING SATURATED GASKETS Filed March 8, 1958 Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE METHOD OF MAKING SATUBATED GASKETS Application March 8, 1938, Serial No. 194,714

14 Claims.

This invention relates to'rings, ellipses, squares, oblongs and various irregular shaped objects made from paper and paper-like or similar cellulosic webs saturated with a liquid medium conslsting of or containing agents which swell cellulose. With regard to its more specific features, the invention is concerned with the manufacture of gaskets from paper or similar cellulosic webs saturated with a binder which consists of or contains agents which swell paper. By the term paper we mean a web consisting essentially of the usual paper-making vegetable or cellulosic fibres or a web containing such fibres in sufficient quantity to cause dimensional changes upon per- 1 meation or impregnation and having associated therewith comminuted cork or leather or other modifying agents.

It is an object of this invention to produce an eflicient gasket with the edges of the gasket well sealed by the impregnating medium. Another object of the invention is to produce a gasket which is highly resistant to the passage of grease, oil, gasoline and similar solvents and which is generally resistant to water. Still another object of the invention is the economical production of a gasket or similar article with tolerances in dimensions which are sufficiently accurate for commercial purposes. Another object of the invention is to provide practical processes by which one or more of the objects mentioned may be readily accomplished. Other objects will be in part obvious or in part pointed out hereafter.

In carrying out the invention we make use of any known machine for the production of paper from stock, as for example, a Fourdrinier machine or a cylinder machine. We provide as a base paper stock, any suitable furnish, for example, rope, chemical wood pulp, purified wood pulp, jute, or combinations thereof, and we may also use a certain amount of cotton or linen fibre.

The manufacture of saturating papers for use in the manufacture of gaskets by saturating the paper with a water solution of glue-glycerine and subsequently tanning is well known in the art. In general we find papers made for use in the existing processes of the prior art satisfactory for use in our process. Various gauges of paper are used in the manufacture of gaskets and we use various gauges in our process. A suitable illustration of an all-fibre paper, satisfactory for our process, may conform to the following specificaions:

Gauge inch .023 Basis weight pounds 194 Basis weight per mil of thickness do 8.4 Glue test, not to exceed seconds 21 The glue test is run by saturating the paper with a solution of 1 part glue, 3 /2 parts glycerine and 7 parts water at 120 F., using in the solui l tion a grease-free bone glue of 38-40 millipoises in viscosity as determined by the standard method of the National Association of Glue Manufacturers. The test is carried out by forming a boat of the paper and dropping it on top of the solution and observing the time required for the glue solution to penetrate through the paper. Such a paper may well be prepared from a fibre furnish consisting of 1 part by weight of rope to 2 parts by weight of jute, but other fibres may be used and the proportion of rope to jute may be varied or the paper may be made solely of one kind of fibres.

We also find that paper made according to the patent of Elmer C. Schacht, No. 1,888,409, issued November 22, 1932, is very satisfactory. As stated in the aforesaid patent to Schacht, such a paper may be prepared from jute, rope, hemp, sisal, kraft pulp fibres, cotton, linen, and long wood pulp fibres, as well as absorbent alpha-cellulose wood pulp fibres, and these fibres are mixed in a heater with the comminuted cork to produce the furnish which is subsequently felted on a paper-making machine to form a light, porous, saturating paper.

In addition to or in lieu of cork we may use other modifying agents along with the usual paper-making fibres such as for instance, disintegrated leather, the use of which is well known in the art.

When gaskets and similar objects. are made from the types of paper herein described, saturated with a solution of glue, glycerine and water, the method has been to saturate a web of the paper, tan the glue and dry, or dry and subsequently tan, after which the gaskets are cut from the dried, tanned, saturated web of paper. This process is very wasteful in that the area of material used in a gasket is small as compared with the spaces. in between the gaskets and the area cut out within the gasket perimeter. Wastes in excess of 25% are common and in many cases the waste is well in excess of 50%, even though an effort is made to use the pieces cut out from inside a gasket to form still smaller gaskets. Furthermore, gaskets made according to the present invention have their edges well sealed with the saturating medium. Gaskets made according to the prior art do not have an outside or external sealing film along the cut edges since they are out after saturation.

The chemicals -used in the saturation of the paper form a substantial part of the raw material cost and it is an object of the present invention to save all or a considerable part of the chemicals that have heretofore been wasted: in that we saturate the gasket or similar article, but do not saturate the waste. Furthermore, waste paper cuttings in the past have not been adapted to reuse in the paper-making machine without special processing because they contained insolubilized protein. In the present processes the paper scrap is suitable for re-use in the papermaking machine and therefore a considerable proportion of the base paper cost may be saved by returning the waste paper to the beater.

We have conducted many tests with a variety of samples of commercial saturating paper and find that in the saturating process there is an increase in the cross dimension of the paper, varying from about 1 to 2.5%, a change which is equivalent to 1 inch to 2% inches per inches of dimension in the gasket material in the cross direction. With such papers the change in the length or machine direction is usually relatively small, or in fact there may sometimes be a slight shrinkage rather than an expansion in the length direction. It is obvious that if a gasket were precut from such paper and subsequently saturated, a circular gasket would become an ellipse after saturation and furthermore that the dimensions of the finished gasket would not be within accepted tolerances for gasket sizes for various applications.

In co-pending application of Nicholas E. Oglesby, Ser, No. 751,235, filed November 2, 1934, a process of pre-cutting and subsequent saturation of gaskets has been disclosed. Essentially this method consists of making gaskets of predetermined size and shape from paper-like material by determining the dimensional change characteristics of the paper upon saturation, pre-cutting a blank of a size and shape to allow for such dimensional changes and subsequently saturating the pre-cut blank.

The. present invention contemplates the formation of gaskets and similar articles of predetermined dimensions and shape by pre-cutting and subsequent saturation or impregnation, it being an object to provide a method which is economical particularly in requirements for dies used to cut the blanks for subsequent saturation.

The present invention comprises (1) the extension or changing of the dimensions of the base paper, as for instance, by swelling the fibres which may be accomplished by fiuid impregnation of the paper, (2) the cutting or a blank from the extended or swollen paper or paper of changed dimensions of substantially the same size and shape as the gasket desired, and (3) subsequent saturation oi the pre-cut blank, sometimes preferably preceded by drying to some extent.

In the practice of our invention we determine the dimensional changes of the paper under consideration when saturated with the desired solution and also pre-determine experimentally the degree 01' dimensional changes such as extension or swelling required at the time the blank is cut, to produce upon saturation with a given-solu tion, a gasket of substantially the same size and dimensions as the pre-cut blank.

The swelling or the paper upon saturation, tanning and drying is a function of both the paper and the saturating solutions used, and the degree of dimensional changes such as extension or swelling required should be determined for the particular paper and saturants in question. Where the paper characteristics are controlled from time to time to be substantially constant and the same saturating solution is used from time to time, it is obviously not necessary to pre determine the degree of dimensional change for each lot of paper. It should further be appreciated that tolerances permitted in gaskets depend upon the use thereof and that a higher degree of control of the final size and shape of the gasket is required in some instances than in others.

As a means of swelling the paper prior to cutting the paper blank, we sometimes subject the paper to a controlled fiuid or moisture treatment, e. g., by water, either as a liquid or in some other fiuid form such as steam, or humid air. The uncontrolled application of fluid, as by saturating the paper with liquid water, usually results in an over-expansion of the paper with the result that a blank cut from such saturated paper when dried and subsequently saturated will not be or the desired size and shape. We, therefore, apply a predetermined, limited quantity of fluid such as water, whereby the paper is swelled to a predetermined extent so that a blank cut from paper so treated, partially or wholly dried and subsequently saturated or saturated without drying, as the case may be, will produce a final gasket of substantially the size and shape of the pre-cut blank. Sometimes at least partial dry ing is desirable as an aid to ready saturation.

The liquid may be supplied, as such, or in another fluid form, such as a vapor or mist; for example, the limited and controlled quantity oi. water required may be applied to the paper either in the form of liquid, steam, or by means of humid air.

Where humid air is used, we normally find that a high humidity is required, sometimes a relative humidity of about 98%. The results oi. experiments with one run of .024 inch cork fibre paper will be given by way of illustration.

The paper was subjected to an atmosphere of about 98% relative humidity at a temperature of about 70 F, A gasket with an outside dimension in the length direction of the paper of 5.010 inches and in the cross direction oi the paper of 5.080 inches was cut. The blank was saturated with a solution consisting of one part glue, 3% parts glycerine and 7% parts water at a temperature of F. The saturated blank was cooled and then dipped in a solution of 5% formaldehyde in water to tan or insolubilize the glue. The blank was then dried and brought to equilibrium with a temperature of 70 F. and a relative humidity of 50%. Its finished dimensions were, in the length direction of the paper, 5.004 inches and in the cross direction of the paper, 5.110 inches. In the length direction 01' the paper the dimension of the finished gasket was 0.12% less than the same dimension oi the precut blank and in the cross direction of the paper the dimension of the finished gasket was 0.59% greater than the same dimension of the pre-cut blank. As a control, a blank was cut from the same paper after it had been brought to equilibrium with a temperature of 70' F. and 50% relative humidity, conditions which are taken as representative of an average of those existing in plants. This blank was saturated with the same glue solution, cooled, tanned and dried and brought to equilibrium with a temperature of 70 F. and 50% relative humidity just as in the case of the blank that had been pre-cut at 98% relative humidity. In the case of this control experiment the dimension of the finished gasket in the length direction of the paper was 0.1% less than the same dimension of the pre-cut blank and the dimension of the finished gasket in the cross direction of the paper was 1.52% greater than the same dimension of the pre-cut blank. The maximum variation of any dimension in the case of the gasket cut at 98% humidity as between the pre-cut blank and the final gasket was 0.59%. In the case of the control experiment where the blank was cut at equilibrium with ordinary atmospheric conditions, the maximum variation was 1.52%, a value well outside oi. commercial tolerances for gaskets. Control experiments and experiments in which the blanks were cut at 98% relative humidity were run with .0115 inch cork fibre paper and .048 inch cork fibre paper. In the control experiments where the methods of the present invention were not employed, the finished gasket in the case of the .0115 inch paper had a dimension in the length direction of the paper which was 0.14% greater than the same dimension in the pre-cut blank, and a dimension in the cross direction of the paper which was 2.5% greater than the same dimension in the pre-cut blank. Similarly, in the control experiment with the .048-inch paper, the finished gasket had a dimension in the length direction of the paper which was 0.06% less than the same dimension in the pre-cut blank and a dimension in the cross direction of the paper which was 1.6% greater than the same dimension in the pre-cut blank.

Where the blanks were pre-cut after being brought to equilibrium at 98% relatively humidity in accordance with the present invention, the variations in dimensions as between the final gasket and the pre-cut blank were much less. In the case of the .0115 inch paper the finished gasket had a dimension in the length direction of the paper which was 0.18% less than the same dimension in the pre-cut blank and a dimension in the cross direction of the paper which was 0.53% greater than the same dimension in the pre-cut blank.

In the case of the .048 inch paper the finished gasket had a dimension in the length direction of the paper which was 0.299% less than the same dimension in the pre-cut blank and a dimension in the cross direction of the paper which was 0.375% greater than the same dimension in the pre-cut blank.

In the same way .0165 inch cork fibre paper and .033 inch cork fibre paper were brought to equilibrium at 98% relative humidity and 70 F. Blanks were pre-cut, saturated, cooled, tanned, dried and brought to equilibrium with 50% relative humidity and 70 F. In the case of the .0165 inch paper the finished gasket had a dimension in the length direction of the paper which was 0.12% less than the same dimension in the pre-cut blank and a dimension in the cross direction of the paper which was 0.33% greater than the same dimension in the pre-cut blank. The gasket made from the .033 inch paper had a dimension in the length direction of the paper which was 0.30% less than the same dimension in the pre-cut blank and a dimension in the cross direction of the paper which was 0.42% greater ,than the same dimension of the pre-cut blank.

It will be seen that swelling by exposure to high relative humidity and then pre-cutting the blanks has substantially decreased the variation in dimensions between the pre-cut blank and the subsequently completed gasket. Where tolerance requirements are not too severe, this method of operation gives sufilciently accurate results.

The characteristics of the cork fibre paper used in the processings given herein by way of illustration, areas follows:

Gauge .0115 inch paper:

Ream weight pounds- '70 Glue saturation test, not over seconds 18 -Furnish- 28-150 mesh cork per cent 15 48-150 mesh cork do 25 Jute do 38 Rope do 22 Gauge .0165 inch paper:

Ream weight "pounds" 9'7 Glue saturation test, not over seconds 19 Furnish 28-150 mesh cork per cent 15 48-150 mesh cork do 25 Jute do 38 Rope do 22 Gauge .033 inch paper:

Ream weight pounds 188 Glue saturation test, not over seconds 25 Furnish- 28-150 mesh cork per cent 40 28-48 mesh cork do 5 Jute do 35 Rope d 20 Gauge .048 inch paper:

Ream weight pounds 265 Glue saturation test, not over seconds 33 Furnish- 28-150 mesh cork per cent 40 28-48 mesh cork do Jute d0 35 Rope do 22 As still further illustrations of the pre-treatment of paper with a controlled quantity of water, we may cite the manufacture of gaskets from paper made from amixedfurnish of rope and jute, in which the two are present to the extent of about 1 part by weight of rope to 2 parts by weight of jute. Such saturating papers are well known in the art.

The paper used was .024 inch thick, had a ream weight of about 195 pounds and gave a glue test of not over 21 seconds.

The paper described was brought to equilibrium with 98% relative humidity and a temperature of 70 F. Blanks were cut from the paper so treated and were allowed to dry after which they were saturated with a solution containing 1 part glue, 3 /2 parts glycerine and 7 parts water. The gaskets were cooled and tanned by dipping in 5% formaldehyde in water and dried to equilibrium with 50% relative humidity and 70 F.

The final gasket had a dimension in the length direction of the paper which was 0.32% less than the same dimension in the pre-cut blank and a dimension in the cross direction of the paper which was 0.33% greater than the same dimension oi the pre-cut blank.

As a variation of the procedure, a portion of the .024 inch paper was brought to equilibrium with 98% relative humidity at a temperature of 70 F. and a blank was cut and saturated immediately without any intermediate drying. The saturating solution used contained 1 part glue, 3% parts glycerine and 7 parts water. After the pre-cut blank had been saturated, it was cooled, tanned by dipping in a 5% solution of formaldehyde in water and brought to equilibrium with a relative humidity of 50% at a temperature of 70 F. The final gasket so formed had a dimension along the length direction of the paper which was 0.14% less than the same dimension of the pre-cut blank and a dimension along the cross direction of the paper which was 0.46% greater than the same dimension in the pre-cut blank.

The operations of the present invention include the saturation of a pre-cut blank with a binder and generally the insolubilizing of the binder and subsequently the drying of the article. These latter operations may be reversed or varied in accordance with known principles or ideas which will occur to those skilled in the art. The various operations may be carried out by hand as described in the tests and experiments or the operations may be carried out continuously with suitable equipment. For instance, it has been found very satisfactory to practice the methods of the invention by using a machine such as the one shown diagrammatically in the accompanying drawing, although many other types of machines may be employed with equal success.

In the accompanying drawing:

Figure 1 is a diagrammatic vertical sectional view of a portion of a machine adapted to carry out our procew;

Figure 2 is a similar view of another portion of the apparatus, and

Figure 3 is a similar view of still another portion of the apparatus.

Referring to Figure 1, a plurality of rolls 5 and I are shown carrying a flexible wire belt 6 through a tank 1 containing a solution 8 which may for example consist of 1 part bone glue, 3 parts glycerine and 7 parts water. The solution may be held at a temperature of 120 F. by any suitable means such as a jacket on the tank or a coil submerged in the liquid. Idler rolls 5 may be used to depress the gaskets II below the surface of the liquid or they may be set so as to allow the gaskets to contact the top of the liquid without being submerged if this type of operation is preferred for any particular type of gasket. Idler rolls I0 may be used to prevent the center of the span of the belt between idler rolls 9 from dropping too deeply into the solution as compared with a smaller drop of the wire belt into the solution in the neighborhood of rolls 5. The gaskets or similar articles II are placed upon the endless wire belt and are carried into or onto the solution as indicated, and saturated, after which they are brushed from the wire belt 6 by a roller brush I2 or other suitable device onto a belt I4. Belt I4 in the fragmentary view in Figure 1 is the same belt as belt ll in Figure 2.

Referring to Figure 2, I2 is the roller brush indicated as I2 in Figure 1. The gaskets II are dumped upon the belt ll by roller brush I2. Belt II is an absorbent felt belt or similar porous belt. The gaskets I I are carried by belt I 4 through rubber rollers II and the excess saturating solution is squeezed from the gaskets by the rollers II and absorbed by the porous felt belt I4. The gaskets are dumped from the belt Il onto a wire belt 2I.

The belt I] is carried by idler rolls II through a tank It containing a solution H which is preferably oi the same composition as solution I in tank I of Figure 1, or thinner, and which, for instance, may be maintained at a temperature of 130 F. and passes between squeeze rolls I 2 which squeeze the solution out of the absorbent belt I 4 so that the belt I4 is continuously rendered absorbent for the excess of solution squeezed from the gaskets II which are fed continuously to the belt I4. Wire belt 2I is carried by rolls I! and may be spread or otherwise supported by additional idler rolls 20 and passes through a refrigerating chamber 22 where the gaskets are cooled, as for instance to 34 to 38 F., and then through a chamber 23 where a tanning agent is sprayed from nozzles 24 onto both the tops and the bottoms of the gaskets, or other articles I I to insolubilize the binder. A suitable tanning agent is a 5% solution of formaldehyde in water and it may be sprayed at a low temperature, as for instance, at a temperature of'40 F. From the belt II the gaskets or other articles are dumped upon a belt 26, shown in a fragmentary view, supported by a roll 25.

Referring to Figure 3, belt 26 of Figure 3 is the same belt as that shown as 26 in Figure 2 and roll 25 in Figure 3 is similar to roll 25 in Figure 2 and carries the other end of belt 26. From belt 26 the gaskets I I are dumped upon a steel belt 29 carried by rolls 28 and the belt extends into a drying chamber 21. At the end of travel of belt 25 the gaskets I I are dumped upon another steel belt 3| within the drying chamber and trained about rolls 30. The gaskets are conveyed by the last mentioned belt lengthwise of the drying chamber and outwardly therefrom. They may be deposited in any suitable container 32 after their complete travel through the drying chamber. The chamber 21 should be kept at a suitable temperature preferably not in excess of 90 F., a good range being between and F. Many well known methods of heating the chamber may be used but it is preferred to circulate heated air therethrough, discarding part of the circulated air and adding new warm air to keep the humidity range between 30 and 40%. The humidity range may, however, be varied within wide limits, depending upon the rate of drying desired.

Instead of controlling the extension or swelling of the paper prior to cutting the blank by controlling the quantity of fluid to which the paper is exposed, we may also limit the swelling power of the fluid and use a larger quantity. For instance, by sufficiently decreasing the swelling power of water, we are enabled to completely wet or saturate the paper without any fine control as to quantity of the water used and produce an extended web of paper from which a blank may be cut and subsequently saturated to produce a gasket having substantially the same dimensions as the pre-cut blank.

For example, the swelling of cellulose by certain salt solutions of suitable concentrations is less than the swelling by pure water.

As illustrations of carrying out this form of the invention, we may cite the treatment of .024 inch cork fibre paper with saturated solutions of ammonium chloride and of calcium nitrate in water.

The paper was soaked in a saturated solution of ammonium chloride at ordinary room temperature for 15 minutes after which it was removed from the salt solution and while the paper was wet and swelled, blanks were cut for subsequent use in the formation of gaskets. The blanks were washed to remove the salt solution which might otherwise produce corrosive gaskets; the washed blanks were dried and then saturated with a solution consisting of 1 part of glue, 3 parts glycerine and 7 /2 parts water. The gasket was cooled, tanned with formaldehyde, dried and measured. A dimension of the gasket in the length direction of the paper was 0.12% less than the same dimension of the original blank, while a dimension of the gasket in the cross direction of the paper was 0.235% greater than the same dimension of the pre-cut blank. By proceeding similarly with a saturated solution of calcium nitrate in water, a final gasket was made in which a dimension of the gasket in the length direction of the paper was 0.219% greater than the same dimension of the pre-cut blank, and a dimension of the final gasket in the cross direction of the paper was 0.255% greater than the same dimension of the pre-cut blank.

The foregoing aspects of the present invention contemplate a controlled swelling of the paper or similar web in which the ability of water to swell the web is limited by dissolving solid bodies in the water. The solid bodies, if corrosive in nature. and if the corrosive nature of the final gasket is important, may be removed by washing after the blank is cut and before saturation with the binder. Otherwise, the solids do not have to be removed and the pre-cut blank may be dried and saturated without an intermediate washing.

We also use fluid agents other than water to control the swelling of the paper. Suitable volatile agents are solutions of water and ethyl alcohol, water and methyl alcohol, or water and acetone. We treat the web ofpaper with these mild cellulose swelling agents, as for instance, by dipping or saturating the paper and we may vary the quantity of water added to the alcohols or acetone to control the expansion in accordance with the result desired. Where the paper. is wet with these solutions, as for instance, methyl alcohol, swelling is relatively rapid and the blanks may be out shortly after wetting. Furthermore, these agents are relatively volatile and are easily removed from the pre-cut blank before its saturation with a binder. Depending upon the economics of the process and the size of the operation, the non-aqueous portion of the wetting solution may or may not be recovered as by passing the vapors, during drying, through a condenser or by absorption in activated charcoal, expulsion, and subsequent re-condensation. Suitable apparatus and methods for such recovery of solvent vapors and their concentration by distillation, if required, are well known in the art.

As a detailed illustration of liquid agents which may be added to water or to which water may be added to produce a milder swelling liquid than water, we may cite by way of illustration, the use of methyl alcohol and'water. As a general p oposition the greater the quantity of alcohol and the smaller the quantity of water in the solution, the less will be the swelling of the cellulose and vice versa.

Separate portions of .024 inch cork fibre paper were saturated by allowing them to stand for 15 minutes in methyl alcohol solutions containing 10, and of water respectively. Then in each case the paper was removed from the solution and blanks were cut, without allowing substantial loss of the solution as by evaporation,

for subsequent saturation to form gaskets. The methyl alcohol and water was allowed to evapo rate or evaporated to dry the pre-cut blanks. The blanks were then saturated with a solution consisting of 1 part glue, 3% parts glycerine and 7% parts water as previously described for this operation. The saturated blanks were allowed to cool and the glue was tanned by immersion in a water solution containing 5% formaldehyde. The saturated and tanned gaskets were then allowed to dry and brought to equilibrium at 50% relative humidity and 70 F.

Where 10% water was used in the methyl alcohol, a dimension of the final gasket in the length direction of the paper was 0.22% less than the same dimension of the pre-cut blank, and a dimension of the final gasket in the cross direction of the paper was 0.46% greater than the same dimension of the pre-cut blank.

Where 20% water was present in the methyl alcohol, a dimension of the final gasket in the length direction of the paper was 0.30% less than the same dimension of the pre-cut blank, and a dimension of the final gasket in the cross direction of the paper was 0.30% greater than the same dimension of the pre-cut blank.

Where 30% water was present in the methyl alcohol, a dimension of the final gasket in the length direction of the paper was 0.30% less than the samedimension of the pre-cut blank, and a dimension of the final gasket in thecross direction of the paper was 0.10% greater than the same dimension of the pre-cut blank.

In still another set of operations with methyl alcohol and water, the cork fibre paper was allowed to stand overnight in the alcohol-water solution. The paper was then removed from the solution and blanks were immediately cut for subsequent saturation. The cut blanks were allowed to dry and were subsequently saturated with a solution consisting of 1 part of glue, 3 parts glycerine and 7 parts of water and then tanned and dried as in previous cases. The gaskets were finally brought to equilibrium at 50% relative humidity and a temperature of 70 F.

Where 5% of water was present in the methyl alcohol, a dimension of the finished gasket in the length direction of the paper was 0.56% less than the same dimension in the pre-cut blank, and a dimension of the finished gasket in the cross direction of the paper was 0.316% greater than the same dimension in the pre-cut blank.

Where 10% of water was present in the methyl alcohol treating solution, a dimension of the finished gasket in the length direction of the paper was 0.64% less than the same dimension in the pre-cut blank, and a dimension of the finished gasket in the cross direction of the paper was 0.14% less than the same dimension in the precut blank.

Where 20% water was present in the methyl alcohol treating solution, a dimension of the finished gasket in the length direction of the paper was 0.60% less than the same dimension in the pre-cut blank, and a dimension of the finished gasket in the cross direction of the paper was 0.53% less than the same dimension in the precut blank.

As a further illustration of the use of volatile agents to modify the swelling power of water, we may cite the treatment of paper .023 inch thick made from one part of rope and two parts of jute. Specifications for such a paper have been previously given herein. The paper was treated with methyl alcohol containing 10% water by dipping the paper in the solution and allowing it to stand in the solution for about '75 minutes. The paper was then removed from the solution and blanks were cut for subsequent saturation.

The blanks were allowed to dry and were then saturated with a solution containing 1 part glue, 3% parts glycerine and 7% parts water as previously described for this operation. The glue was tanned and the saturated gaskets were allowed to dry to equilibrium with relative humidity and 70 F. The finished gasket had a dimension in the length direction of the paper which was 0.438% less than the same dimension in the pre-cut blank and a dimension in the cross direction which was 0.078% less than the same dimension in the pre-cut blank.

Other percentages of water in methyl alcohol were tried and of those tried it was found that 10% water in the alcohol to pre-expand the web before cuttlngflthe blanks resulted in the formation of a gasket with dimensions suiilciently close to those of the pre-cut blank for the practical applications for which kets were intended.

As a control experiment a blank was cut from the same paper which had not been pre-treated in accordance with the present invention. The blank was then saturated with the same solution of glue and glycerine in water and otherwise handled in the same way. The gasket so made had a dimension inthe length direction of the paper which was 0.15% less than the same dimension of the pre-cut blank, and a dimension in the cross direction of the paper which was 1.11% greater than the same dimension in the pre-cut blank.

We may also treat the paper web with relatively non-volatile swelling agents such as glycerine, sorbitol, tri-ethylene glycol and diethylene glycol which may be introduced in any suitable fluid form. Of these we use glycerine and sorbitol more often and sorbitol, being the less volatile, is a preferred swelling agent of the non-volatile type. Where glycerine, sorbitol and the like are applied to the paper as swelling agents, the paper may be subsequently dried and the blanks for subsequent saturation to form gaskets, may be cut from the dried paper.

This method contemplates, therefore, the preparation of a paper web from which blanks may be pre-cut and subsequently saturated with a given solution to yield a finished gasket of substantially the same shape and size as the blank pre-cut from the treated paper. Conventional saturating paper may be treated as by saturation with a water solution containing the required quantity of the swelling agent such as glycerine, sorbitol and the like and the paper may be dried in any convenient way as for instance by passing over drying cans or by festooning. Festooning has certain advantages over can drying in some cases in that the paper may be dried without substantial tension as a result of which there is less shrinkage in the cross direction during the drying operation and the paper web therefore swells correspondingly less when subsequently saturated with a binder containing an agent 'eifective in swelling cellulose. Drying without substantial tension so that there will be relatively free and unrestrained shrinkage in all directions, serves the further useful purpose of producing a web which has more uniform expansion and contraction characteristics from the edge to the center than one dried on cans under relatively high tenthe particular gassion. Furthermore, where cans are used to dry the web, the use of low tension and exercise of (are with reference to uniformity of rate of drying across the web, is conducive to improved results.

This preferred form of the invention in which relatively now-volatile swelling agents are used, also comprehends the treatment of the paper web during the paper making process with such a swelling agent, as for instance, by tub sizing so that the paper is continuously formed and treated to produce a web from which blanks may be out which are suitable for saturation with the desired solution to produce a finished gasket which approaches the size and shape of the pre-cut blank. If the non-volatile swelling agents are added during the paper making process they may be added to a wet, newly formed web and the web may be subsequently dried or they may be added after considerable or even all of the water has been removed from the paper.

Depending upon the economics of the process, the glycerine, sorbitol or other non-volatile swelling agent may be recovered from the waste scrap of the web formed during the cutting of blanks as by leaching with water and subsequently concentrating the leached swelling agent,as byevaporation of parts or all of the water. Where operations are carried out on a large scale, it will normally pay to recover and re-use the swelling agent left in the scrap before the scrap is returned to the beater for re-use in forming paper.

We preferably use a swelling agent of the same type as that subsequently used in the modified glutinous or similar binder so that the swelling agent used as a pro-treatment may form a part of the final binder mixture within the gasket.

The use of relatively non-volatile swelling agents as described has many advantages from the standpoint of simplicity of operation. For instance. the paper can be treated during the paper making operation which will often prove more economical than treatmentafter the web has been formed, dried and removed from the paper machine. Furthermore, paper so treated can be dried to ordinary atmospheric conditions and the blanks can be out without having to guard against evaporation of the more volatile agents like water and alcohol whereby the dimensions 01' the swollen web might change before the blank is cut.

In addition to adding glycerine, sorbitol or similar agents to the web during its formation or after it is formed, we may also add along with such swelling agent or agents, a portion of the glutinous or other binder in which case wet strength is imparted to the web and the subsequently cut blanks will be tough and readily handled without damage in the final saturating process. A small portion of glue added in the pretreatment with a swelling agent may be tanned if the highest wet strength is to be developed with a small quantity of glue and the tanning may readily be accomplished by the use of formaldehyde, potassium bichromate and similar agents known in the art. Relatively large quantities of glue added in the pretreatment are preferably not tanned, as such tanned glue would render the waste less suitable for re-use in the beater of the paper machine.

In carrying out our invention where non-volatile swelling agents such as glycerine and sorbitol are used, small trial blanks should be cut and treated with different percentages of glycerine or sorbitol or similar agent, and dried to some constant humidity and temperature such as 50% relative humidity and 70 It, and the blanks should be subsequently saturated with the solution that it is intended to use in practice as for instance, a solution containing glue, glycerine and water in proportions to yield in the final.

gasket, 1 part of glue to 3% parts glycerine, or a solution containing glue, sorbitol and water in proportions to yield in the final product, 1 part glue to 3% parts sorbitol. Diilerent proportions of glue, glycerine and water, or glue, sorbitol and water are used, depending upon the result desired. The use of greater quantities of glycerine or sorbitol gives a more flexible product but the use of relatively greater quantities of glue and less of glycerine or sorbitol give a product with higher tensile strength. The final balance as between fiexibility and other characteristics varies with the intended use.

Normally the final or binder saturating solution used is adjusted to allow for the glycerine or sorbitol included in the pre-treated paper, the glycerine or sorbitol or similar agent used as a pretreatment serving as a part of the final binder.

As an illustration of the use of glycerine in the pre-treatment of the formed web from which blanks may be cut and saturated with a flexibilized, glutinous hinder, or similar binder, we may cite results obtained with .a certain cork fibre sheet, .024 inch thick. Paper was treated with various concentrations of glycerine and water. illustrations of the concentrations tried being 12% glycerine dissolved in water; 14% glycerine dissolved in water; 15% glycerine dissolved in water; 16% glycerine dissolved in water and 17 glycerine dissolved in water. Separate portions of the paper were treated with each of the concentrations of glycerine by thoroughly saturating. After the paper had been thoroughly saturated, it was removed from the treating solution and dried to equilibrium at about 50% relative humidity and 70 F., that is, to about average room temperature and humidities. Paper blanks were then cut from each of the treated papers. During the saturating operation the paper was weighed, both before and after saturation with the swelling solution, so that the absorption of the glycerine could be computed. Where a 12% solution of glycerine was used, the paper absorbed 27.4% of its own weight of glycerine; where a 14% solution of glycerine was used, the absorption of glycerine was 32.6% of the paper weight; where 15% glycerine was used, the absorption oiglycerine was 35.1% of the weight of the paper; where 16% glycerine was used, the

absorption was 37.6% of the weight of the paper and where 17% glycerine was used, the glycerine absorption was 40.1% of the weight of the paper. It was desired that the final gasket contain of the paper weight as glue and glycerine and that the glue and glycerine be in the ratio of 1 part glue to 3 /2 parts glycerine. It was then computed and determined that the blank cut from paper pre-treated with 14% glycerine should be saturated with a solution consisting of 1.23

parts glue, 2.29 parts glycerine and 11.2 parts water. Upon saturation of the blank cut from paper treated with 14% glycerine with this predetermined solution, the desired quantity of glue and glycerine was obtained in the final gasket. In a similar way, computations and determinations were made for each of the other examples and the blanks were saturated with the determined solution of glue, glycerine and water to produce a final product containing 90% oi the base paper weight as glue-glycerine with the glue and glycerine present in the ratio of 1 part glue to 3% parts glycerine.

After the blanks were saturated with the determined solutions they were cooled and tanned by dipping in a 5% solution of formaldehyde in water. The saturated gaskets were then dried and brought to equilibrium with ordinary atmospheric conditions, that 'is, about 50% relative humidity and a temperature of 70 F.

In the case where 12% glycerine dissolved in water was used to pre-treat the web, a dimension of the final gasket along the length direction of the paper was 0.1% less than the same dimension of the pre-cut blank and a dimension of the final gasket along the cross direction of the paper was 0.396% greater than the same dimension in the pre-cut blank.

In the case where 14% glycerine was used to pre-treat the web, a dimension of the final gasket along the length direction of the paper was the same as the same dimension of the pre-cut blank and a dimension of the final gasket along the cross direction 0! the paper was 0.197% greater than the same dimension in the pre-cut blank.

Where 15% glycerine dissolved in water was used to pre-treat the web, a dimension of the final gasket along the length direction of the paper was 0.1% less than the same dimension of the pre-cut blankand a dimension of the final gasket along the cross direction of the paper was 0.059% less than the same dimension in the pre-cut blank.

Where 16% glycerine dissolved in water was used to pre-treat the web, a dimension of the final gasket along the length direction of the paper was 0.34% less than the same dimension of the pre-cut blank and a dimension of the final gasket along the cross direction of the paper was 0.294% less than the same dimension in the pre-cut blank.

Where 17% glycerine was used to pre-treat the web, a dimension ofthe final gasket along the length direction of the paper was 0.34% less than the same dimension of the pre-cut blank and a dimension of the final gasket along the cross direction of the paper was 0.39% less than the same dimension in the pre-cut blank.

As a further illustration of the use of nonvolatile swelling agents, we may cite the results obtained with a cork fibre paper .024 inch thick, wherein sorbitol was used as the non-volatile swelling agent. Separate portions of paper were treated with solutions containing 12% sorbitol dissolved in water; 14% sorbitol dissolved in water; 15% sorbitol dissolved in water; 16% sorbitol dissolved in water and 17% sorbitol dissolved in water. Blanks were cut from each of the treated papers for subsequent saturation to form gaskets. v

The absorption of sorbitol, that is, the sorbitol left in the paper after saturation was, in the case where a 12% solution of sorbitol was used, 27.65% of the paper weight. In the case where a 14% solution or sorbitol was used, 33.4% of sorbitol was left in the paper; in the case of the 15% solution of sorbitol, 35.9% sorbitol was left in the paper; in the case of the 16% solution of sorbitol dissolved in water, 38.4% of sorbitol was left in the paper and in the case of the 17% solution of sorbitol, 40.9% of sorbitol was left in the paper. It was desired that the final product contain 90% of the paper weight as glue and sorbitol and that the glue and sorbitol be present in the ratio of 1 part glue to 3 /2 parts sorbitol. Computations were therefore made and tests,

as necessary, were made to determine the saturating binder solution that should be used to give the final desired result in the saturated gasket.

'Ihe blanks were then saturated with the Dredetermined solutions of glue, sorbitol and water, cooled, tanned, dried and brought to equilibrium at ordinary atmospheric conditions, that is, about 50% relative humidity and a temperature of 70' F.

The dimensions of the gaskets so made were determined and it was found that in the case a! the paper pre-treated with 12% sorbitol in water, a dimension or the final gasket along the length direction 01' the paper was 0.18% less than the same dimension of the pre-cut blank and that a dimension of the final gasket along the cross direction of the paper was 0.298% more than the same dimension of the pre-cut blank.

In the case where the paper was pre-treated with 14% sorbitol, it was found that a dimension of the final gasket along the length direction oi the paper was 0.145% less than the same dimension of the pre-cut blank and a dimension of the final gasket along the cross direction the paper was 0.396% more than the same dimension oi the pre-cut blank.

In the case where 15% sorbitol in water was used to treat the paper, it was found that a dimension of the final gasket along the length direction of the paper was 0.10% less than the same dimension of the pre-cut blank and that a dimension of the finished gasket along the cross direction oi the paper was 0.139% less than the same dimension oi the pre-cut blank.

In the case where the paper was treated with 16% sorbitol in water, it was found that a dimension of the final gasket along the length direction of the paper was 0.28% less than the same dimension of the pre-cut blank and that a dimension of the finished gasket along the cross direction oi the paper was 0.217% less than the same dimension of the pre-cut blank.

In the case where the paper was treated with 17% sorbitol in water, it was found that a dimension oi the final gasket along the length direction of the paper was 0.28% 18% than the same dimension of the pre-cut blank and that a dimension of the finished gasket along the cross direction of the paper was 0.296% less than the same dimension of the pre-cut blank.

As a further citation of the use 01' non-volatile swelling agents to prepare a paper web from which blanks may be cut when the paper is substantially dried and subsequently saturated to produce finished gaskets of substantially the same size and shape as the pre-cut blanks, we may cite the use 01' 14% glycerine dissolved in water to treat various gauges of cork fibre paper. In one case the paper was .0115 inch thick and the final gasket produced by the method described had a dimension in the length direction oi the paper which was 0.221% less than the same dimension oi the Dre-cut blank and a dimension in the cross direction of the paper which was 0.158% less than the same dimension in the precut blank.

In another case the cork fibre paper used was .0165 inch thick and the final gasket produced by the method described had a dimension in the length direction 01 the paper which was 0.042% less than the same dimension of the pre-cut blank and a dimension in the cross direction of the paper which was 0.394% greater than the same dimension in the pre-cut blank.

Another lot of cork fibre paper, .024 inch thick,

aim-r74 was used in the process described. The final gasket had a dimension in the length direction of the paper which was 0.06% less than the same dimension of the pre-cut blank and a dimension in the cross direction of the paper which was 0.090% greater than the same dimension in the pre-cut blank.

In still another case, the cork fibre used was .033 inch thick, and the final gasket had a dimension in the length direction of the paper which was 0.20% less than the same dimension of the pre-cut blank and a dimension in the cross direction oi the paper which was 0.09% greater than the same dimension of the pre-cut blank.

In still another case where the cork fibre paper was thicker, that is, .048 inch thick, 9. final gasket was produced which had a dimension along the length direction of the paper which was 0.02% less than the-same dimension of the pre-cut blank, and a dimension along the cross direction oi the paper which was 0.04% greater than the same dimension of the pre-cut blank.

It will therefore be seen that the non-volatile swelling agents such as glycerine and sorbitol have been so used as to form a web of paper from which blanks may be cut when the paper is dried and subsequently saturated with a predetermined binder containing an agent which swells cellulose to produce a final gasket which approaches the s ze and shape of the pre-cut blank, and that the difilculty due to large changes in shapes and dimensions or shapes or dimensions when saturated and dried to form a gasket, has been overcome in that we have provided a paper web which is not subject to such magnitudes of changes in dimensions when saturated with solutions of binders which have heretofore caused excessive changes in the dimensions of the paper when used as saturants, dried and tanned in the normal way.

It will furthermore be seen that the methods of the present invention provide practical processes of manufacturing saturated gaskets and other articles from paper and paper-like webs containing cellulosic fibres in amount which will cause the paper to change dimensions upon saturation and a binder which swells cellulosic fibres by precutting a blank for the gasket or other article, which upon saturation with a solution which swells cellulose, and subsequently drying, will produce a gasket or other article with dimensions and shape which approach the dimensions and shape of the pre-cut blank, thus making practical (1) the pre-cutting oi gaskets and similar articles, (2) the saving of a substantial proportion or all of the chemicals that have heretofore been lost in the waste, and (3) the re-use of the waste cuttings in a paper beating machine without any complicated treating process such as might be required to remove the insolubilized binder from the waste.

In the examples of our processes given by way of illustration, we have used a binder containing bone glue and glycerine or bone glue and sorbitol. Other binders may, however, be used as for instance, hide glue may be used in lieu of bone glue and casein may be used to replace part or all 01' the glue.

Our processes are, however, of more general application and may be used to overcome the dimensional changes resulting from various binders which cause swelling and distortion or other dimensional changes similar to those encountered with the solutions given herein by way of illustration. For instan it the binders or saturating media are of the type which shrink the fibers or the paper we use in our preliminary treatment a dimensional changing means or medium which will suitably shrink the paper. the gasket is to be finely impregnated with resins or drying oils which have a shrinking action, the preliminary shrinkage may be eflected either by the use of suitable fluid shrinking media or, if desired, by heating at elevated temperatures and low humidity to dehydrate and shrink the cellulose. The blank will, of course, be out after it has been shrunk and the procedure is as heretofore described.

Furthermore, in the illustrative examples given herein, formaldehyde has generally been used to insolubilize the glue or similar binder. Other tanning or insolubilizing agents may, however, be

used, as for instance, paraformaldehyde or tannic acid. While generally less suitable, such tanning agents as potassium bichromate and chrome alum may be used.

The sorbitol used in certain examples of this invention is a grade sold by the Atlas Powder Company. It is a thick, viscous syrup of commercial grade containing about 83% sorbitol, the balance being water except for about 1% of sodium sulphate and about 0.75% of glucose.

In saturating the pre-cut blanks in accordance with the various forms of this invention, different percentages of binder are incorporated in the paper or paper-like material, the amount of binder used depending, for instance, upon the paper, the binder, and the intended use of the article. For many purposes, however, dried binder within the range of about to about of the base paper weight will be found satisfactory.

The terms saturating and impregnating are used throughout the specification and claims in a generic sense to cover the incorporation of a suitable amount of a saturating or impregnating agent in the body of the paper, as distinguished from mere surface painting or coating. Where we refer to controlled fiuid application we mean the treatment with a fluid in either selectively predetermined quantity or character, or both.

The terms blank and pre-cut blank as used in this specification and in the claims mean articles cut from the unsaturated web by dies or other suitablemean's known to the art, of approximately the size and shape as desired in the final fabricated gasket or other article and are called blanks or pre-cut blanks up until the time the saturating process has been completed.

It should be appreciated that the articles of our invention are distinguished from the articles of the prior art in that the cut edges of our articles are filmed over by the binder and are well saturated by the binder, whereas the articles of the prior art have not had their edges filmed over and penetrated in the same way by the binder, since the gaskets of the prior art are cut from a saturated web.

We claim:

- l. A process of making saturated paper gaskets of definite size and shape from paper containing cellulosic fibres in an amount which will cause the paper to change dimensions upon saturation, comprising swelling the paper to a degree controlled in accordance with the charac teristics of the paper and the bfnder used for saturation thereof, cutting a blank from the paper in such a swollen condition and subsequently saturating the blank with a binder containing an agent which swells cellulose whereby For example, if

the final dried saturated article has substantially the same shape and the same dimensions in the plane of the paper as the pre-cut blank.

2. A process of making saturated gaskets of predetermined size and shape from paper-like material, including cellulosic fibres in an amount which will cause the paper-like material to change dimensions upon saturation withf a binder solution which swells cellulose, comprising changing the dimensions of the paper to a degree controlled in accordance with the characteristics of the paper-like material and the binder used for saturation thereof, cutting a blank from the said paper-like material having a dimensional area and shape such that after saturation with such a binder and bringing to equilibrium with average atmospheric conditions the article will assume a desired size and shape, saturating the said blank with such a binder and drying, whereby the saturated article assumes the desired size and shape, the area and shape 01' said dried saturated article in the plane of the web being substantially the same as the area and the shape of the blank cut from said paper-like material with changed dimensions.

3. A process of making saturated gaskets of definite size and shape from a web containing a substantial proportion of cellulosic fibres whereby the web is extended by the saturating medium, comprising extending the dimensions of the web to a degree controlled in accordance with the characteristics of the web and the binder used for saturation thereof by applying to the web a controlled quantity of water whereby a blank cut from the web so extended has a substantially reduced tendency to change shape and dimensions when saturated with a binder which swells cellulose, and subsequently dried and cutting a blank from the web in such an extended condition and subsequently saturating the blank with a solution which swells cellulose, and drying the saturated web to produce a gasket which has the desired shape and dimensions.

4. A process of making saturated gaskets of definite size and shape from a web containing a substantial proportion of cellulosic fibres whereby the web is extended by the saturating medium, comprising extending the dimensions of the web to a degree controlled in accordance with the characteristics of the web and the binder used for saturation thereof by treating with a water solution containing an agent which limits the swelling power of the water whereby a blank cut from the web in such an extended condition has a materially reduced tendency to change size and shape when saturated with a saturating medium which swells cellulose, cutting a blank from the web in such an extended condition and subsequently saturating the blank with the said saturating medium and drying the blank to produce an article of the desired size and shape.

5. A process of making saturated gaskets of pre-determined size and shape from a web con taining a substantial proportion of cellulosic fibres whereby the fibres are swelled by the saturating medium and the dimensions of the web are changed, comprising treating the web after its formation and prior to cutting a blank therefrom with a solution of a relatively non-volatile agent which swells cellulose, drying the web so treated to produce a web with low dimensional change characteristics when saturated with the saturating medium, cutting a blank from the web so prepared and subsequently saturating and drying to produce a finished article of the desired size and shape, said final 'size and shape inthe plane of the web not difieri'ng substantially from the size and shape of the blank cut from the treated web prior to saturation.

6. A process of making saturated gaskets of definite size and shape from a web containing a substantial proportion of cellulosic fibres and a saturating medium which swells cellulose, comprising treating the web with a relatively nonvolatile agent which is etl'ective in swelling cellulose in pre-determined amount whereby a blank cut from said treated web has a reduced tendency to change in shape and dimensions when saturated with a ,pre-determined medium, drying the web, cutting -a blank from the dried web, and saturating the blank with the predetermined medium to produce a finished article which when dry is of the pre-determined size and shape, the shape and size of said finished article in the plane of the web being substantially the same as the shape and the size oi the blank cut from the treated web prior to saturation.

7. A process of making saturated gaskets of pre-determined size and shape from paper-like material including cellulosic fibres in an amount which will cause the paper to change dimensions upon saturation with a binder solution which swells cellulose, comprising treating the paperiike material with a solution containing water and a volatile organic agent which is effective in limiting the swelling of the cellulosic fibres I by the water, cutting a blank from the paperlike material so treated, drying the blank to remove a substantial proportion of the added water and organic agent, saturating the blank with a binder which swells cellulose and drying to produce an article of the desired size and shape whereby the article in the plane of the paper-like material has an area and shape which do not differ substantially from the area and the shape of the blank cut from the treated paperlike material prior to saturation.

'8. A process of making saturated gaskets of pre-determined size and shape from paper-like material, including cellulosic fibres in an amount which will cause the paper to change dimensions upon saturation with a binder solution which swells cellulose, comprising treating the paperlike material after its formation and prior to cutting a blank therefrom with a controlled amount of a solution of an agent selected from the group consisting of glycerine and sorbitol, drying to remove a substantial proportion of the solvent and bringing the web to equilibrium with average atmospheric humidities, cutting a blank from the web so prepared and subsequently saturating with the pre-determined binder whereby a gasket of the desired size and shape is obtained.

9. A process of making saturated gaskets of pro-determined size and shape from a web containing a substantial proportion of cellulosic fibres whereby the fibres are swelled by the saturating medium and the dimensions of the web are changed, comprising treating the web after its formation and prior to the cutting of a blank with a pre-determined amount of an agent selected from the group consisting of glycerine and sorbitol, drying the web so treated to produce a web with low dimensional change characteristics when saturated with the saturating medium, cutting a blank from the web so prepared;,and

subsequently saturating with a binder solution comprising glue and an agent selected from the group consisting of glycerine and sorbitol, and drying to produce'a finished article of the desired size and shape and whereby the size'and shape of the finished article in the plane of the web do not differ substantially from the size and shape of the blank cut from the prepared web prior to saturation.

10. A process of making saturated gaskets of pre-determined size and shape from a web containing a substantial proportion 01' cellulosic fibres whereby the fibres are swelled by the saturating medium and the dimensions of the web are changed, comprising treating the web after its formation and priorto cutting a blank therefrom with a relatively nonwolatile agent which swells cellulose to produce a web with low dimensional change characteristics when saturated with the said saturating medium, cutting a blank from the web so prepared and subsequently saturating to produce a finished article of the desiredsize and shape and whereby the size and shape of the article in the plane of the web do not differ substantially from the size and shape of the blank cut from the prepared web prior to saturation.

11. A process of making saturated gaskets of pre-determined size and shape from a web containing a substantial proportion of cellulosic fibres and a saturating medium which changes the volumes of the individual fibres and the dimensions of the web, comprising subjecting the web after its formation and prior to cutting a blank therefrom to a controlled treatment to change the volumes of the individual fibres and the dimensions of the web, cutting a blank from the web so treated and subsequently saturating with a pre-determined saturating medium to produce a finished article of substantially the size and shape of the pre-cut blank in the plane of the web.

12. A process of making saturated gaskets of predetermined size and shape from a web containing cellulosic fibres in an amount sufiicient to change the dimensions of the web by shrinkage when the web is impregnated with a saturating medium having a shrinking eifect, comprising subjecting the web after its formation and prior to cutting a blank therefrom to treatment controlled in accordance with the characteristics of the web and the binder used for saturation thereof to shrink the same, cutting a blank from the web so treated and subsequently saturating with a predetermined saturating medium having a shrinking effect to produce a finished article of substantially the size and shape of the pre-eut blank in the plane of the web.

13. A process of making saturated gaskets of pre-determined size and shape from paper-like material including cellulosic fibres in an amount which will cause the paper to change dimensions upon saturation with a binder solution comprising glue and glycerine, including swelling the paper-like material to a degree controlled in accordance with the characteristics oi the paper-like material and the binder used for saturation thereof whereby a blank cut from the swelled paper-like material has a reduced tendency to change in shape and dimensions when saturated with a binder solution, comprising glue and glycerine, and cutting a blank from said swollen paper-like material having dimensional area and shape such that after saturation with such a binder and brin in to q li ri w h average atmospheric conditions, the article assumes a desired size and shape, saturating the said blank with a binder solution comprising glue and glycerine and drying, whereby the saturated article assumes the desired size and shape.

14. A process of making saturated gaskets of pre-determined size and shape from paper-like material including cellulosic fibres in an amount which will cause the paper to change dimensions upon saturation with a binder solution comprising glue and sorbitol, including swelling the paper-like material to a degree controlled in accordance with the characteristics 01 the paperlike material and the binder used for saturation thereof whereby a blank cut from the swelled paper-like material has a reduced tendency to change in shape and dimensions when saturated with a binder solution, comprising glue and sorbitol and cutting a blank from said swollen paper-like material having dimensional area and shape such that after saturation with such a binder and bringing to equilibrium with average atmospheric conditions, the article assumes a desired size and shape, saturating the said blank with a binder solution comprising glue and sorbitol and drying, whereby the saturated article assumes the desired size and shape.

ELMER C. SCI-IACHT. NICHOLAS E. OGLESBY. 

